Protected metal article and method of making the same



A. w. COFFMAN March 9, 1937.

PROTECTED METAL ARTICLE AND METHOD OF MAKING THE SAME Filed Aug. 7, 1936w Ill/V5076;

ing the present Patented 9 1937 I PROTECTED METAL ARTICLE AND METHOD OFMAKING. THE SAME Alden W. Cofi'man,

H. H. Robertson Pittsburgh,- Pa., assi gnor to ompany, Pittsburgh, Pa.,a

corporation of Pennsylvania Application August 7, 1936. Serial No.94,808

This invention relates to a protected metal article and to a method ofmaking the same.

One object of the invention is to provide a novel and superior protectedmetal article which is particularly useful for building' p poses such asroofing and siding material, which is capable of withstanding mechanicalshock in cold weather, which may be formed into various shapes withminimum liability of damage to the protective coatings thereof, and also'which is extremely durable and possesses superior fire resistance ascompared with other protected me articles heretofore manufactured.

Another object of the invention is to provide a is novel and improvedmethod by which the protected metal article may be made at minimumexpense and in a rapid and efiicient manner.

With these general objects in view and such others as may hereinafterappear, the invention consists in the protected-metal article, in themethod of making the same and also in certain novel steps in the methodhereinafter described and particularly pointed out in the claims at theend of this specification.

In the drawing, Fig. 1 illustrates a cross sectional view of a protectedmetal article embodyinvention; Figs. 2 and 3 are sectional viewsillustrating the apparatus preferably employed In general, the presentinvention contemplates an improved protected metal article produced bythe process hereinafterto be described and which comprises a metalarticle In preferably a metal sheet such as an iron or steel sheet. Themetal 35 sheet ID has secured to the opposite surfaces thereof layers l2of fibrous material, preferably asbestos paper or felt, by an interposedmetal adhesive M. The metal adhesive completely envelopes the metalsheet l0 and-may comprise zinc, tin, cadmium lead or other alloy and themetal adhesive is alloyed to the metal sheet l0 and keyed or anchored tothe fibers comprising the fibrous layers l2. In order to furtherdescribed, it is preferred to saturate or impregnate the fibrous .layerswith saturant or an impregnant preferably comprising a bituminouscomposition such as asphalt or any of the other commercial impregnantsnow used for impregnating fibrous layers. The saturated protected metalsheet thus far described is further protected against weather, gas andfume conditions and for the purpose oi. increasing the durability of theprotected sheet and, as herein shown, the

protected metal article is provided with an outer in practicing thepresent process.

atively high protect the article thus far a weather-proofing coating l6which may comprise any desired compositi'onof bituminous material andpreferably a composition comprising cottonseed pitch, and asphalt meltedtogether and which possesses satisfactory weather resistance anddurability.

In producing the present protected metal article it is preferred toafllx the fibrous layers [2 to the metal sheet I ll immediately afterthe metal sheet has passed through a bath of the molten metal adhesiveand before the latter has solidified inproducing the preferred protectedmetal sheet. Zinc is preferably" used as the metal adhesive and asillustrated in the drawing, 20 represents, more'or lessdiagrammatically, the usual galvanizing bath to which steel sheets l8are conveyed from the usual. storage tank IT. The steel sheets areconducted throughthe galvanizing bath in the manner usually practiced inproducing galvanized steel sheets where they receive thezinc coating.galvanizing practice the temperature of the bath of zinc within thegalvanizing pot 20 runs from 830 F. to-8'Z5" F., and the usual fluxesare utilized in the flux box l9 and upon the exit rolls 2i. After thesheets l8 leave the exit rolls 2| and come solidified, provision is madefibrous layers I 8 to one or both surfaces of the sheets. As hereinshown, supply rolls of such fibrous material preferably asbestos felt,are mounted within enclosures 25by which they are protected from thefumes, moisture, etc., evolving from the composite sheet by reason ofthe rel- From the supply rolls the fibrous webs 26 are conducted aroundheating rolls 24 by which moisture is removed from the fibrous materialand the webs are then conducted between combining rolls indicated at 22,23 and between which the metal sheets l8 with the molten zinc coatingthereon are passed. The combining rolls 22, 23 cooperate to firmlyimpress .the fibrous material into the molten zinc produced is conductedfrom the rolls on a suitable conveyor indicated generally at 28. Whenthe sheet has-become cooled and the zinc coating solidifies, the fibrouslayers are firmly bonded to the metal sheet by the zinc coating which isalloyed to the opposite surfaces of the metal sheet l8 and is also keyedto the fibrous While the composite protected sheet in the condition thusfar described may be used with advantage for many purposes, neverthelessfor some purposes I prefer to impregnate the fibrous" layers l2.

In accordance with the usual for applying temperautre of the zinccoatings.

coating and the composite sheet thus layer or layers of the sheet withan impregnant or saturant such as asphalt, and it is preferred toimpregnate the composite sheet while the'temperature thereof isrelatively high. The exact temperature at which it may be found mostdesirable to impregnate the fibrous layer or layers of the compositesheet will depend, of course, upon the temperature and composition ofthe impregnating material, and the temperature of the sheet may becontrolled by the length of the conveyor 28 or by any convenient coolingor heating methods. The impregnation of the fibrous lay.- ers has beenfound to take place much more rapidly when the composite sheet isimpregnated while hot and the degree of impregnation-produced has beenfound to be more complete.

As herein shown, after the composite sheet has left the conveyor 28 itis submerged beneath the surface of a bath of impregnating'materialwithin an elongated tank 30, and as herein shown is deposited upon aconveyor 32 by which it is caused to traverse through the bath and to beelevated at the exit end of the bath to pass through a pair of squeezerolls 34 by which the excess of impregnating material is removed andpermitted to return to the bath. Thereafter the impregnated sheet may beconveyed'on a suitable conveyor indicated generally at 35.

From the description thus far it will be observed thatin practicing thepresent process it is essential to apply the fibrous webs 26 to the zincor other metal adhesive coating as soon as practicable after thegalvanizing or other coating bath, and while the distance from the exitrolls 2| at which this operation may be performed varies withinreasonable limits, care should be taken for best results to apply thefibrous layers before the zinc or other coatings have solidified to anyextent. In practice, operating upon i2, i4 and I6 gauge steel sheets adistance from the exit rolls of the galvanizing bath to the combiningrolls 22, 23, of approximately five to seven feet has been foundsatisfactory.

The asbestos paper or felt commercially obtainable usually embodies asubstantial amount of organic binder, and after such asbestos felt hasbeen applied to the moltenzinc coatings in the manner above described,the heat in the coatings and in the steel sheet operates to burn out asubstantial part of the organic matter. This removal of the minorproportion of the organic matter, however, does not destroy thecontinuity of the asbestos layer and the resulting product has beenfound to be capable of being impregnated more thoroughly or morecompletely as a result of this burning of the organic binder.

The extent to which the organic matter is removed depends upon thetemperature of the galvanizing pot and the thickness of the metal sheetgoverns the amount of heat stored in the metal sheet,-so that thethicker the steel sheet the more complete the removal of the organicmatter from theTasbestos sheets. When operating upon thin steel sheetssupplemental heating means may be utilized if the removal of the organicmatter is found to be insufficient-for any particular pur- From theabove description, it will be understood that in addition to the abovedescribed the application of the fibrous layer or layers at thegalvanizing pot, the fibrous layer or layers may be applied to the metalsheet or member immediately following the application of a tame, tincadmium, or any other suitthe metal sheet l8 has left able alloy coatingwhich may be used as the metal adhesive.

In order to further protect the metal article against weather conditionsand particularly against severe fume conditions, it is preferred toenvelop the composite sheet or article either before or after saturationor scribed, in a bituminous weather-proofing coating and as' illustratedherein, after leaving the impregnating bath the composite sheet ispassed between coating rolls 38,. H. The bituminous composition. inmolten condition may be flowed from a supply tank, indicated at 42, tocoating tanks 40, 46 in which the coating rolls 38, 44 run. As thecomposite sheet passes between the coating rolls, the. desired layers 21of bituminous material,- such as a cotton seed pitch-asphaltcomposition, are applied to the opposite surfaces of the sheet and intheir molten condition fuse together over the sides of the sheet formingthe weather proofing envelope shown at i6.

From the foregoing description it will be observed that the presentprocess, involving the application of the fibrous layers upon the metaladhesive before the solidification or cooling of the metal adhesivesubsequent to the passage of the metal sheet through the bath of themolten metal adhesive, lends itself to continuity of operation andaccompanying economy in the manufacture of the composite sheet, and alsoof the weatherproofed protected metal sheet. In addition to the economyin the manufacture of the products it has been found that in theproducts produced by the process described in which the fibrous'layersare applied before the metal adhesive has cooled or solidified, thefibrous layers adhere to the metal in an improved and superior 'manner.The fact that the metal adhesive is not reheated reduces to a minimumthe formation of metal oxide on the surface of the metal adhesivecoating, thus making it possible for the metal adhesive tointer-penetrate more completely with the fibrous layers, producing asuperior and much firmer bond. When zinc is employed as the metaladhesive, the present process also produces a minimum of the zinc ironalloy layer between the pure zinc and the steel comprising the metalmember i0, and as a result there is less tendency for flaking off of thezinc coating, so that in the products produced by the process a superiorbond and improved durability results. The present process also has theadvantage that a minimum amount of the zinc or other metal in the metaladhesive coating is lost by oxidation and by penetration into the steelso that a maximum layer of pure zinc or other metal is available thuscontributing to the uniformity with which the fibrous layers may beembedded in the pure zinc or other metal adhesive.

The protected metal article embodying the fibrous layers i2 united tothe metal member [0 by the interposed layer of metal adhesive i4,produced in accordance with the present process, and also embodying theenvelop iii of weatherproofing bituminous material as described, is lessinflammable than other comparable products heretofore produced; it mayjected to shock at very low temperatures without removal of theprotective coatings, thus contributing to the durability of theprotected metal article, particularly when used as a roofing or sidingmaterial, and in addition the protected metal sheets may be formed intovarious shapes and corrugated with-minimum liability of damage to theprotective coatings be frozen and sub- In the practical impregnation asdespread across the steel sheet l0, and as a result, after corrosion hasstarted and this protective film has been developed, the

film in place.

Another important the structure of the present protected metal sheetresides in the improved ability of the protective coatings to remain inplace in the event that the is subjected to under such conditions.

in a continuous manner. I

4. As a new article of manufacture, a protected metal article comprisinga metallicsheet, an asbestos sheet and an interposed layer of metaladhesive, whereinthe asbestos sheet is afllxed to the metal sheet by themetal adhesive in its molten condition, as initially applied to themetal sheet, and'wherein the asbestos Sheet is keyed advantage resultingfrom to the metal adhesive when said metal adhesive has solidified and aprotective bituminous coating covering the fibrous material.-

5. As a new article of manufacture, a protected metal article comprisinga metallic sheet, an asbrous materi 6. As a new article of manufacture aprotected metal article comprising a metallic. sheet,

in a continuous manner and a protective bituminous coating covering thefibrous material.

7. Ajcontinuous method article, the steps comprising applying layers oi.fibrous material to the opposite surfaces 01' a metal sheet providedwith a layer of molten base member. 12. A continuous tallic elementswhich 13. A continuous method for fabricating metallic elementscomprising passing a metallic base member through a bath of fiuidmetallic adhesive maintained at a temperature sufficient to raise thetemperature of the metallic base member, as it is .passed therethrough,to the point where the metallic adhesive alloys with the base member,and thereafter applying fibrous material thereto, before the appliedmetallic adhesive has solidified, whereby to firmly key and the metalbase member.

14. As a new article of manufacture, a protected metal articlecomprising a metallic sheet, an asbestos sheet and an interposed layerof metal adhesive. wherein the metal adhesive in its molten condition,as initially applied to the metal sheet. alloys with the metal sheet andpenetrates into the asbestos sheet to key the asbestos sheet to themetal adhesivewhen the latter has solidified and a weather-proofing andanchor the fibrous material to the metallic sheet members.

bituninous coatinz enveloping the composite sheet thus formed.

15. As a new article of manufacture, 9. protected metal articlecomprising a metallic sheet, an asbestos sheet and an interposed layerof metal 5 adhesive, wherein the metal adhesive in its molten condition,as initially applied to the metal sheet, alloys with the metal sheet andpenetrates into the asbestos sheet to key the asbestos sheet to themetal adhesive when the latter has solidified, said asbestos sheetbeingimpregnated with bituminous material.

18. 'As a new article of manufacture, a protected metal articlecomprising a metallic sheet, an asbestos sheet and an interposed layerof metal adhesive, wherein the metal adhesive in. its molten condition,as initially applied to the metal sheet, alloys with the metal sheet andpenetrates into the asbestos sheet to key the asbestos sheet to themetal adhesive when the latter has soliditied and provided with aprotective bituminous coating enveloping the composite sheet thusformed.

